Background and details
Vertical bone regeneration for posterior mandibular placement of a unit implant: non-reabsorbable membrane vs. reabsorbble membrane.
Introduction
The absence of an unitary molar can result in a serious re-absorption of the edendula crest in a horizontal and vertical sense (Seibert, 1983).
According to the principles of guided bone regeneration, for bone reconstruction to be performed with predictability, the bone graft used should be covered with a barrier material (membrane) that can be reabsorbed or non-reabsorbed (Jovanovic, 1992). Jensen, 1995 Simion, 1995).
In cases where bone regeneration The use of re-absorbable or non-reabsorbable membrane is performed only horizontally and does not make a great difference, as with an extensive area of vascular contribution, the graft will be revascularized quickly, usually at a time less than the re-absorbment of the membrane (Dahlin, 1989, 1990, 1991 a and b). Ogiso, 1991 Buser, 1991 and 1994 Schenk, 1994). Nevertheless, vertical bone regeneration has a number of limitations (Tinti, 1996). Jovanovic, 1992):
• A lower source of osteogenic cells and lower vascularization.
• Increased difficulty with primary closure with suture and risk of dehiscence of the wound.
• It's necessary to use autogenous bone pilling material as an autogenic bone mixture with a biomaterial.
• Increased healing time (9-12 months).
The non-reabsorbed membrane ensures the isolation of the graft by its barrier effect throughout the healing time, so that the more time the membrane gets put into place the more mature will be the regenerated bone (Buser, 1990). Nyman, 1990 Becker, 1991 Botticelli, 2003). That simple principle allows us to make vertical bone regeneration using particulate bone, by making sure that a long time of healing will allow for the incorporation of all bone particles that we have put under the membrane to the new regenerated bone, avoiding the risk that soft tissue cells will be put into bone chips, which could occur after an earlier reabsorbed membrane.
Reabsorbable membranes maintain their barrier properties for 2-4 months (LundgreN, 1997). Hammerle, 1998 Kohal, 1999) with that, if we are to avoid risks during regeneration
They should be used as a bone graft and using monocortical blocks. The use of a mono-cortical block would dampen the effect of early membrane re-absorption, with this as a function only of the time necessary to conduct the revascularization and nutrition of the bone block, so that when membrane re-absorption occurs, the graft has been "accepted and incorporated" into the recipient bone bed and re-absorption by having the cortical surface of the bone block in contact with the suretayacent soft tissue at least (Spray, 2000).
Objective
To present two cases where there was an absence of the first lower left molar and in both cases there was a vertical and horizontal deficit of bone that prevented an implant from being put into place. One of the cases was treated with vertical guided bone regeneration using particulated autogenous bone graft covered with non-reabsorbed membrane while the other was treated with a monocortical block of autogenous bone from the mint covered with reabsorbed membrane.
Patients and methods
Case I
A patient with an absence of the first lower left molar, with a 4 mm vertical bone deficit at the edendulum site preventing an implant from being placed at the ideal prosthetic site (Figure 1).
surgical procedure
Fingercover was lifted and spread from the canine area to the retromolar area, autogenous bone chips from the retromolar area were obtained (Figure 2) and the particulated bone was placed onto the edendula area. Once well adapted, all bone chips were covered with a pTFER membrane and with titanium reinforcement to avoid collapse onto the recipient bone bed (Figures 3 and 4) and the flap was sutured without tension (Figure 5). Two weeks later, the points were withdrawn.
Reentry
The surgical re-entry was followed by 366 days later with the aim of withdrawing the membrane and placing an implant (Figures 6 and 7).
The flap was lifted at total thickness (Figure 8) and the membrane was perfectly adapted and with no sign of infection (Figure 9). The membrane was removed and after monitoring a complete
A 4 x 11 mm Astra Tech implant was put up to the highest level with complete resolution of the vertical defect (Figures 10 and 11) and was left unsubmerged by a transmuted healing pillar (Figures 12-15).
Following a 3-month healing period, a porcelain metal crown was put up and an optimal state of soft and hard tissues after a year of scarring was observed (Figure 16).
Case II:
A patient with an absence of the first lower left molar (Figura1) and an edentum site had a vertical bone deficit of 5 mm (Figure 2) that prevented an implant from being placed at an ideal prosthetic site. Due to the mesialization and inclination of the second lower molar, it was decided to straighten 37 by using a micronil placed at the backstage. Once the 37 was in good position, a vertical guided bone regeneration of the edendula bone crest was performed.
surgical procedure
Two shortcuts were raised: the first at the level of the 36 edendula (recipient bed) area (Figure 3) where a horizontal and vertical defect of about 5 mm (Figure 4) was observed and the second at the level of the donor area between canine and canine (Figure 5) from where a monocortical block of the mint area was obtained and the same defect was placed at the edendula area with a screw, so that some of the bone graft was closely adapted to the elbow and another remains at a bone level (Figure 6).
Once the stability of the block had been checked, it was covered with a reabsorbable collagen membrane (Figure 7). Following the fixation of the membrane with titanium pinchetes, the flap was sutured without tension (Figures 8-10). Two weeks later his points were withdrawn.
Reentry
Due to the patient's personal motif, an implant placement surgery was performed 18 months later (Figure 11). Fingered up at total thickness (Figure 12), and after monitoring complete bone regeneration to the best possible level with complete resolution of the bone defect, the clawing screw was removed and broken after trying to remove it (Figure 13). Following an impossible withdrawal, although bone was even removed from a horizontal direction (Figures 14 and 15) to achieve a clamping surface, it was decided to maintain and place an Astra Tech 4 x 11 mm implant (Figures 16 and 17) that was left unsubmerged by a transmuted scarring pillar (Figure 18).
A porcelain metal crown (Figure 19) was put after a 3-month healing period and an optimal state of soft and hard tissues after a year of healing was observed.
(Figure 20).
Discussion
Both cases have been achieved with a vertical and horizontal guided bone regeneration up to the best possible level that was to regenerate both bone and the interproximal bone level of adjacent teeth. In both cases, the bone had good quality, with a vital and bleeding look and with primary stability from the implants.
The benefits of using the non-reabsorbable membrane were:
• Regradative surgery less traumatic and less invasive as bone chips from the adjacent area are easily obtained.
The disadvantages of non-reabsorbable membrane use were:
• A very difficult surgical technique for the placement and attachment of the membrane.
• Increased risk of exposure and accordingly of infection during healing.
It's the author's opinion that the reabsorbable membrane should be avoided in cases of vertical regeneration unless the pilling material is a corticomedular block.
If bone chips are used, membrane re-absorption could result in a colonization of bone graft by soft tissue cells and a significant limitation of the amount of vertical bone regeneration obtained.
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